An integrated chip typically comprises a plurality of different layers, which are processed according to different patterns. The various patterns used in depositing layers and/or doping regions on a semiconductor substrate are often defined by a process called photolithography.
A photolithography process is generally performed by first spin coating a layer of light sensitive photoresist layer onto the surface of a semiconductor substrate. A photomask is then used to selectively expose the photoresist layer to radiation (e.g., visible or ultraviolet light) to form patterns of exposed areas of the photoresist layer. After exposure, the photoresist layer is subjected to a chemical developer, which removes exposed areas of photoresist, selectively exposing areas of an underlying layer.